In the field of LED drive technology, PWM dimming and analog dimming are two commonly used dimming techniques. Among them, the PWM dimming is often used in deep dimming applications. However, the PWM dimming current is chopped, which creates a large ripple on the output current and becomes a potential EMI interference source. The analog dimming has good performance when a dimming depth is relatively shallow, but when the deep dimming is required, the dimming depth that can be achieved by the analog dimming is limited by a maximum operating frequency allowed by the switching device, or it may be limited by a maximum ripple current of an inductor, which makes the inductor current intermittent and affects a linearity of the analog dimming.
Therefore, it is necessary to provide a method to solve at least one of the foregoing problems.